Neutralized caseins are produced by precipitating the protein fraction of milk or milk products with acids to produce acid casein and then neutralizing the acid casein with an alkali. The neutralized casein is referred to as the salt, or caseinate, of the corresponding alkali. However, it has never been entirely clear in the art that the neutralized caseins are, indeed, salts, at least in the usual sense of the word. In the present invention, the evidence does not point to a salt, per se, and therefore the term "neutralized casein" will be used herein to describe the present material and to emphasize the difference over conventional materials of the present nature, which may be properly called caseinates.
As noted above, acid casein is precipitated from milk or milk fractions by the action of an acid (with or without the aid of a milk clothing enzyme, e.g., a rennet enzyme). For example, lactic acid may be added to milk or milk fractions or produced in situ from organisms grown therein, and the corresponding lactic casein will precipitate. Alternately, a mineral acid, such as hydrochloric acid, may be added to the milk or milk fraction to precipitate the acid casein. The acid casein is usually treated with a base to form the caseinate (principally sodium hydroxide to form sodium caseinate).
Whether the casein is in the form of a caseinate or acid casein, the art has long appreciated that the casein contains over 90% protein and can provide an exceptionally important source of protein for foodstuffs. However, the acid caseins have a relatively unpleasant "acid" taste and the caseinates have a relatively unpleasant consistency in the mouth (referred to as mouth-feel), i.e., a somewhat soapy mouth feel. In view thereof, the amount of either acid casein or conventional caseinate which may be added to foodstuffs is considerably limited. Generally speaking, foodstuffs will not contain more than about 5% of the acid casein or caseinate or otherwise the unpleasant flavors and consistencies adversely affect consumer acceptance of the foodstuff.
The art has long sought ways of treating acid casein and caseinate so as to render the taste and mouth-feel more acceptable to the consuming public. Some success has been met in these regards and as a result, higher proportions of acid casein and caseinate are now possible in conventional foodstuffs. Nevertheless, the acid casein and caseinate previously available contain more objectionable flavor and consistency components than is desirable and the taste and mouth-feel of foodstuffs containing these greater amounts of the casein or caseinate are often adversely affected.
In co-pending applications Ser. Nos. 276,168 and 276,169, both filed on July 28, 1972, processes are described for improving the blandness of caseinates. In one process, a caseinate, e.g., sodium caseinate, is slowly heated with a magnesium salt, e.g., magnesium chloride, to produce a more bland caseinate. In the other process, the caseinate is rapidly mixed with a hot solution of the salt. While these processes do, indeed, produce a bland product, substantial amounts of the caseinate are lost in the solution due to the high solubility of the sodium caseinate. Thus, the processes considerably increase the cost of the recovered caseinates. Further, the product still has some undesired mouth-feel and taste, which is now believed to be a result of the residual amounts of sodium or calcium (from the starting caseinates) which remain in the product. Also, the physical properties of the product are not as desired, especially in regard to mixing with aqueous compositions.
It would, therefore, be of advantage in the art to provide an extremely bland casein which can be incorporated in foodstuffs in relatively large amounts and which does not have undesired taste or mouth-feel.